Tribological evaluation of the streaming mode performance of metal evaporated and metal particle tapes

A commercial Hi-8 VCR was instrumented to measure the friction force between the rotary heads and tape, rms head output and signal dropouts to sub-μs durations. Streaming mode experiments at design tension using metal evaporated (ME) and metal particle (MP) tapes were performed in which the tapes were subjected to repeated play/rewind cycling. Long wavelength waviness of the ME tape surface and a large number of sharper asperities on the MP tape surface affected the magnetic and tribological performance of the tapes. The friction force and head output generally increased, and the dropout frequency (number of dropouts/min) generally decreased as the tapes were worn smooth. Head-to-tape spacing and dropout frequency decreased more for MP tape, as compared to ME tape. On the ME tape surface, damage initiated at high points or bumps, which resulted in weakening of the metal coating at these locations. Cracks initiated at these locations grew (driven by longitudinal tension) laterally across the tape width and connected localized damage areas at tape failure after 840 play/rewind cycles. MP tape performance improved gradually through 1000 play/rewind cycles. Based on this study, ME tape is less durable than MP tape, and reduced waviness of the ME tape surface could further improve ME tape performance